MAISTRA-2648: WASM fix for s390x

Fixes WASM on s390x https://issues.redhat.com/browse/MAISTRA-2648
Corresponding proxy-wasm/proxy-wasm-cpp-host PRs:
proxy-wasm#198
proxy-wasm#282

Author: knm3000

include/proxy-wasm/exports.h

@@ -74,12 +74,13 @@ template <typename Pairs> size_t pairsSize(const Pairs &result) {
 
 template <typename Pairs> void marshalPairs(const Pairs &result, char *buffer) {
   char *b = buffer;
-  *reinterpret_cast<uint32_t *>(b) = htowasm(result.size());
+  bool reverse = "null" != contextOrEffectiveContext()->wasmVm()->runtime();
+  *reinterpret_cast<uint32_t *>(b) = reverse ? htowasm(result.size()) : result.size();
   b += sizeof(uint32_t);
   for (auto &p : result) {
-    *reinterpret_cast<uint32_t *>(b) = htowasm(p.first.size());
+    *reinterpret_cast<uint32_t *>(b) = reverse ? htowasm(p.first.size()) : p.first.size();
     b += sizeof(uint32_t);
-    *reinterpret_cast<uint32_t *>(b) = htowasm(p.second.size());
+    *reinterpret_cast<uint32_t *>(b) = reverse ? htowasm(p.second.size()) : p.second.size();
     b += sizeof(uint32_t);
   }
   for (auto &p : result) {

src/exports.cc

@@ -65,16 +65,22 @@ Pairs toPairs(std::string_view buffer) {
   if (buffer.size() < sizeof(uint32_t)) {
     return {};
   }
-  auto size = wasmtoh(*reinterpret_cast<const uint32_t *>(b));
+  bool reverse = "null" != contextOrEffectiveContext()->wasmVm()->runtime();
+  auto size = reverse ? wasmtoh(*reinterpret_cast<const uint32_t *>(b))
+                      : *reinterpret_cast<const uint32_t *>(b);
   b += sizeof(uint32_t);
   if (sizeof(uint32_t) + size * 2 * sizeof(uint32_t) > buffer.size()) {
     return {};
   }
   result.resize(size);
   for (uint32_t i = 0; i < size; i++) {
-    result[i].first = std::string_view(nullptr, wasmtoh(*reinterpret_cast<const uint32_t *>(b)));
+    result[i].first =
+        std::string_view(nullptr, reverse ? wasmtoh(*reinterpret_cast<const uint32_t *>(b))
+                                          : *reinterpret_cast<const uint32_t *>(b));
     b += sizeof(uint32_t);
-    result[i].second = std::string_view(nullptr, wasmtoh(*reinterpret_cast<const uint32_t *>(b)));
+    result[i].second =
+        std::string_view(nullptr, reverse ? wasmtoh(*reinterpret_cast<const uint32_t *>(b))
+                                          : *reinterpret_cast<const uint32_t *>(b));
     b += sizeof(uint32_t);
   }
   for (auto &p : result) {
@@ -690,7 +696,8 @@ Word wasi_unstable_fd_prestat_dir_name(Word /*fd*/, Word /*path_ptr*/, Word /*pa
 // Implementation of writev-like() syscall that redirects stdout/stderr to Envoy
 // logs.
 Word writevImpl(Word fd, Word iovs, Word iovs_len, Word *nwritten_ptr) {
-  auto *context = contextOrEffectiveContext();
+  auto context = contextOrEffectiveContext();
+  bool reverse = "null" != context->wasmVm()->runtime();
 
   // Read syscall args.
   uint64_t log_level;
@@ -712,10 +719,11 @@ Word writevImpl(Word fd, Word iovs, Word iovs_len, Word *nwritten_ptr) {
     if (!memslice) {
       return 21; // __WASI_EFAULT
     }
-    const auto *iovec = reinterpret_cast<const uint32_t *>(memslice.value().data());
-    if (iovec[1] != 0U /* buf_len */) {
-      memslice = context->wasmVm()->getMemory(wasmtoh(iovec[0]) /* buf */,
-                                              wasmtoh(iovec[1]) /* buf_len */);
+    const uint32_t *iovec = reinterpret_cast<const uint32_t *>(memslice.value().data());
+    if (iovec[1] /* buf_len */) {
+      auto iovec0 = reverse ? wasmtoh(iovec[0]) : iovec[0];
+      auto iovec1 = reverse ? wasmtoh(iovec[1]) : iovec[1];
+      memslice = context->wasmVm()->getMemory(iovec0 /* buf */, iovec1 /* buf_len */);
       if (!memslice) {
         return 21; // __WASI_EFAULT
       }

src/signature_util.cc

@@ -93,7 +93,7 @@ bool SignatureUtil::verifySignature(std::string_view bytecode, std::string &mess
   }
 
   const auto *signature = reinterpret_cast<const uint8_t *>(payload.data()) + sizeof(uint32_t);
-  const auto sig_len = payload.size() - sizeof(uint32_t); 
+  const auto sig_len = payload.size() - sizeof(uint32_t);
 
   SHA512_CTX ctx;
   SHA512_Init(&ctx);
@@ -108,8 +108,10 @@ bool SignatureUtil::verifySignature(std::string_view bytecode, std::string &mess
   static const auto ed25519_pubkey = hex2pubkey<32>(PROXY_WASM_VERIFY_WITH_ED25519_PUBKEY);
 
   bool retval = true;
-  EVP_MD_CTX* mctx(EVP_MD_CTX_new());
-  EVP_PKEY* key(EVP_PKEY_new_raw_public_key(EVP_PKEY_ED25519, NULL, static_cast<const unsigned char*>(ed25519_pubkey.data()), ed25519_pubkey.size()));
+  EVP_MD_CTX *mctx(EVP_MD_CTX_new());
+  EVP_PKEY *key(EVP_PKEY_new_raw_public_key(
+      EVP_PKEY_ED25519, NULL, static_cast<const unsigned char *>(ed25519_pubkey.data()),
+      ed25519_pubkey.size()));
 
   if (key == nullptr) {
     message = "Failed to load ed25519 public key";
@@ -119,15 +121,16 @@ bool SignatureUtil::verifySignature(std::string_view bytecode, std::string &mess
     message = "Failed to initialize ed25519 digest verify";
     retval = false;
   }
-  if (retval && !EVP_DigestVerify(mctx, signature, sig_len, hash, sizeof(hash))) { 
+  if (retval && !EVP_DigestVerify(mctx, signature, sig_len, hash, sizeof(hash))) {
     message = "Signature mismatch";
     retval = false;
   }
 
   EVP_PKEY_free(key);
   EVP_MD_CTX_free(mctx);
 
-  if (retval) message = "Wasm signature OK (Ed25519)";
+  if (retval)
+    message = "Wasm signature OK (Ed25519)";
   return retval;
 
 #endif

test/runtime_test.cc

@@ -81,6 +81,24 @@ TEST_P(TestVm, StraceLogLevel) {
   EXPECT_TRUE(host->isTraceLogged("[host<-vm] run return: void"));
 }
 
+TEST_P(TestVM, Memory) {
+  auto source = readTestWasmFile("abi_export.wasm");
+  ASSERT_TRUE(vm_->load(source, {}, {}));
+  ASSERT_TRUE(vm_->link(""));
+
+  Word word;
+  ASSERT_TRUE(vm_->setWord(0x2000, Word(100)));
+  ASSERT_TRUE(vm_->getWord(0x2000, &word));
+  ASSERT_EQ(100, word.u64_);
+
+  uint32_t data[2] = {htowasm(static_cast<uint32_t>(-1)), htowasm(200)};
+  ASSERT_TRUE(vm_->setMemory(0x200, sizeof(int32_t) * 2, static_cast<void *>(data)));
+  ASSERT_TRUE(vm_->getWord(0x200, &word));
+  ASSERT_EQ(-1, static_cast<int32_t>(word.u64_));
+  ASSERT_TRUE(vm_->getWord(0x204, &word));
+  ASSERT_EQ(200, static_cast<int32_t>(word.u64_));
+}
+
 TEST_P(TestVm, TerminateExecution) {
   // TODO(chaoqin-li1123): implement execution termination for other runtime.
   if (engine_ != "v8") {